This invention relates to deflection windings including both saddle-wound and toroidally-wound portions for deflecting an electron beam to form a line on the screen of the kinescope.
Television displays are ordinarily formed on the lighted raster area on the screen of a kinescope. The raster is formed by repetitively scanning one or more electron beams over the phosphor-coated screen. The repetitive scanning is accomplished by high-speed scanning along horizontal lines, together with a relatively slow-speed scanning in a vertical direction. The deflection of the electron beams in broadcast television receivers is by means of deflection windings through which the appropriate deflection current flows. A deflection yoke for a kinescope may include a pair of windings adapted for horizontal deflection, a further pair of windings adapted for vertical deflection, an annular or toroidal magnetic core, and may also include ancillary windings for correcting the various distortions which occur in the formation of the raster. Such ancillary windings may include dynamic convergence and quadrature windings.
Energy is stored in magnetic fields produced by the deflection windings. In order to conserve energy and reduce power consumption, the energy is recirculated through the deflection circuit associated with the winding. The deflection circuit and the deflection winding have resistance, and the resistance causes a portion of the energy being circulated to be lost as heat. In the case of horizontal deflection, recirculation occurs about 15,750 times each second, and reduction of the losses is of paramount concern. Thus, the horizontal deflection windings in the prior art are often configured as saddle windings. Saddle windings have less leakage fields than the equivalent toroidal winding, resulting in less energy stored in the magnetic field of the windings during each deflection cycle and consequently less recirculation loss.
The vertical deflection windings in the prior art may be configured as either saddle or toroid windings. Toroidal windings may have the advantage of shorter conductor length than the equivalent saddle winding, and allow precision conductor placement.
In the highly competitive commercial television field, cost considerations make the shorter conductor length of the toroidal winding very desirable. Even though the stored energy is higher, toroidal vertical deflection windings are often used, since the stored energy is recirculated only 60 times a second, and the dissipative losses are commensurately smaller than at the higher horizontal frequency. Also, the shorter conductor length of the toroidal winding reduces the resistance of the deflection winding, thereby mitigating the losses resulting from the increased leakage fields. Windings having conductor lengths less than those of a saddle winding and leakage less than those of a toroid winding might be advantageous for both horizontal and vertical use.